Owner request: 'now add #help with short list of all command'. Registered in
the CommandService constructor next to #ping; returns a SINGLE multi-line
string (one packet, ~203 chars) — not an array, which would drip-feed one
spaced packet per line through the v0.21.5 MESH_MULTI_SEND_DELAY_MS loop.
Also hardened the v0.21.5 multi-send-spacing spec: its wall-clock assertion
('first send < 8 ms after t0') flaked under full-suite load — replaced with
fake timers, which assert deterministically that line 1 is out before any time
elapses and lines 2-3 land exactly one delay apart.
kamilkrzywda